Why the possession of momentum and initiative is all-important in the case of left governments:

"Even when a Left government really controls state branches and apparatuses, it does not necessarily control the one or ones which play the dominant role in the State and which therefore constitute the central pivot of real power. The centralised unity of the State does not rest on a pyramid whose summit need only be occupied for effective control to be ensured. Moreover, even when a Left government manages to gain control of the hitherto dominant apparatus, the state institutional structure enables the bourgeoisie to transpose the role of dominance from one apparatus to another. In other words, the organization of the bourgeois State allows it to function by successive dislocation and displacement through which the bourgeoisie's power may be removed from one apparatus to another: the State is not a monolithic bloc, but a strategic field. Given that their rigidity makes the state apparatuses resistant to straightforward manipulation by the bourgeoisie, this permutation of apparatus dominance evidently takes place not overnight but according to a relatively lengthy process; this lack of malleability may thus act to the disadvantage of the bourgeoisie and create a breathing-space for the Left in power. Still, the very process of permutation tends to reorganize the centralized unity of the State around the newly dominant apparatus - an apparatus which thereby becomes the supreme refuge-centre of bourgeois power in the State, remaining in operation as such throughout the period of Left government. This complex mechanism may assume several forms, certain of which appear paradoxical. Thus, institutions-apparatuses that normally have an altogether secondary, or purely decorative function may suddenly take on a decisive role: the British House of Lords recently blocked nationalization bills of the Labour government; under Allende, the law courts suddenly discovered an irresistible vocation for guaranteeing 'legality'; and various constitutional councils have at times played a similar role."